Edema, by definition, is the presence of excess fluid in body tissue. An adult male weighing 70 kilograms is composed of about 50% fluid, nominally water, amounting to about 40 liters, approximately 25 liters of which is intracellular and about 15 liters extracellular. Edema occurs in both extracellular fluid compartments as well as intracellular fluid spaces. Although there are many causes of edema, the two most prevalent are heart failure and kidney disease nephrosis in which generalized systemic edema causes pulmonary failure with acute respiratory distress syndrome, and simultaneous pre-renal acute kidney failure. Fluid management systems for addressing such specific systemic conditions have been developed utilizing techniques and apparatus disclosed in U.S. Pat. Nos. 4,950,224, 5,151,082, 5,152,743, 5,224,926, 5,242,382, 5,735,809, 5,968,004, 5,980,478 and 5,980,481. The disclosures of the aforesaid patents are incorporated herein by reference.
A number of edemic conditions, although not systemic, occur in segmented sections of the body. For example, xe2x80x9cElephantitusxe2x80x9d occurs when the lymph nodes in the lower extremities are blocked by infection, especially filarial nematodes resulting in localized edema. Blockage of lymph nodes by cancer, e.g., breast cancer, causes localized edema. Vascular bi-pass procedures can also induce severe localized edema. For treating such localized edema, it is far more preferable and proficient to treat the segment of the body affected rather than attempting to reduce systemic edema of the entire body which could result in negative side effects. However, current therapeutic methods for treating segmental edema involve complex physical therapy utilizing a modality of repeated massage techniques designed to enlist parallel lymphatic paths to relieve blocked lymph circulation. Such techniques are somewhat empirical in nature and have great variation in efficacy. These therapies also are used with special compression garments and/or bandages which must be continuously adjusted over time to fit changing needs of the patient. Oral and topical drugs such as Benzo-pyrones are often combined with the aforesaid therapeutic methods, resulting in long-term treatment, often six months to years before significant results are achieved.
The present invention is directed to means for the selective reduction of localized edemas in substantially reduced time for palliative results. The method of treating segmental edema according to the present invention comprises inserting a plasma extraction filter device in a major vein of a body segment or servicing the body segment containing the edemic tissues, and inserting a return catheter in a major artery of the body segment affected or feeding the body segment from which plasma is extracted. Blood plasma and plasma proteins extracted from the edemic body segment through the plasma extraction filter are directed to an ultrafiltration apparatus where plasma water is separated from the plasma proteins. Plasma proteins are returned to the body segment from which the plasma was extracted via the return catheter in the major artery of the subject body segment. Additional steps and techniques as well as the apparatus used for carrying out the method of the invention will be disclosed in further detail hereinafter.